Input: pxrc - new driver for PhoenixRC Flight Controller Adapter

This driver let you plug in your RC controller to the adapter and
use it as input device in various RC simulators.

Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Documentation/input/devices/pxrc.rst

@@ -0,0 +1,57 @@
+=======================================================
+pxrc - PhoenixRC Flight Controller Adapter
+=======================================================
+
+:Author: Marcus Folkesson <marcus.folkesson@gmail.com>
+
+This driver let you use your own RC controller plugged into the
+adapter that comes with PhoenixRC [1]_ or other compatible adapters.
+
+The adapter supports 7 analog channels and 1 digital input switch.
+
+Notes
+=====
+
+Many RC controllers is able to configure which stick goes to which channel.
+This is also configurable in most simulators, so a matching is not necessary.
+
+The driver is generating the following input event for analog channels:
+
++---------+----------------+
+| Channel |      Event     |
++=========+================+
+|     1   |  ABS_X         |
++---------+----------------+
+|     2   |  ABS_Y         |
++---------+----------------+
+|     3   |  ABS_RX        |
++---------+----------------+
+|     4   |  ABS_RY        |
++---------+----------------+
+|     5   |  ABS_RUDDER    |
++---------+----------------+
+|     6   |  ABS_THROTTLE  |
++---------+----------------+
+|     7   |  ABS_MISC      |
++---------+----------------+
+
+The digital input switch is generated as an `BTN_A` event.
+
+Manual Testing
+==============
+
+To test this driver's functionality you may use `input-event` which is part of
+the `input layer utilities` suite [2]_.
+
+For example::
+
+    > modprobe pxrc
+    > input-events <devnr>
+
+To print all input events from input `devnr`.
+
+References
+==========
+
+.. [1] http://www.phoenix-sim.com/
+.. [2] https://www.kraxel.org/cgit/input/